You could post the EPROM files you have online somewhere for other people to take a quick look. Maybe create a thread on the vcfed forum and add them as an attachment to a message there. If you zip them up they should be small enough for an attachment.
I have only tried using IDA Pro a couple of times. I haven't learned how to use it well enough to be what I have used for similar 8-bit CPU disassembly tasks in the past. I have just written my own basic functionality 8085 / Z80 / 8051 disassemblers when I have had the need. Not too hard to make it smart enough to be able to specify known entry points (for example reset and interrupt vectors) and have it do reachable code traversal from there. Some things require manual intervention and iterative refinement, for example any indirect jumps through call tables, or calculated jumps. Using a professional tool might be quicker, but you might learn a lot more along the way doing things yourself.
